1. Field of the Invention
The present invention relates to the field of exercise equipment and, more particularly, to a self-spotting apparatus for free-weights.
2. Description of the Related Art
Despite the variety of exercise and muscle-building equipment and activities available, free-weight lifting continues to be the workout method of choice for many athletes. Free-weight lifting allows unrestrained motion during lifting, closely approximating application of human strength in many recreation and sporting activities. Selection of weights utilized in free-weight lifting is highly repeatable as compared to machines employing levers, cams, and resistance elements such as springs and hydraulic or pneumatic cylinders. Also, free-weights provide uniform resistance unaffected by wear of mechanical parts and other components.
One disadvantage limiting use of free-weights is the need for one or more spotters, especially in strength regimens that push the strength and endurance limits of the user. These regimens are most effective when the user continues repetitions until he or she is unable to lift the weight. This is a safety concern if spotters are not immediately available since the user may be unable to safely lift the weight to a support device. Even when spotters are available, they may not recognize an unsafe condition, or, their response may not be quick enough to prevent injury.
Self-spotting machines, disclosed by others, have addressed eliminating the need for one or more spotters. For example, U.S. Pat. No. 4,949,959 discloses a barbell assist device utilizing a motor-driven yoke assembly. The yoke assembly provides cables that extend around sheaves and downwardly from each end of the housing to support a barbell over a weight bench. U.S. Pat. No. 5,048,826 discloses a device utilizing a winch assembly to retract and release cables supporting the barbell. U.S. Pat. No. 5,310,394 discloses a spotter system for weightlifters employing a pneumatic piston and cylinder. The cylinder provides lift assistance to the barbell through a lever arm, chain drive, pulley and cables.
None of the aforementioned devices provides independent support of both ends of the barbell, nor do they disclose use of the spotting equipment with dumbbells, a popular free-weight. Nor, do any of these references disclose a positive method of ensuring user-control of the weights before disengaging weight support.
U.S. Pat. No. 4,998,721 discloses a weightlifter""s exercise apparatus utilizing two motor-assisted assemblies supporting a barbell through cables attached to each end. Although the two motors allow independent assist from each side, no positive method is disclosed to ensuring user-control of the weights before disengaging the supports.
U.S. application Ser. No. 09/201,434, disclosed by the applicant and hereby incorporated by reference, discloses a barbell safety spotting apparatus utilizing two rotary pawl clutches that engage respective chain assemblies connected to barbell support cables. Use of two rotary clutches allows independent motion of the support cables and therefore also the ends of the barbell. The rotary pawl clutches utilize solenoids which engage the clutch and J-shaped indentations which require removal of the weight bias caused by the free-weight before the clutch can disengage. When the clutches are engaged, the free-weights are supported, raised or lowered by a drive unit. When the clutches are disengaged, the cables allow independent and full-range motion of the free-weights.
Application Ser. No. 09/201,434 apparatus makes a significant step forward in providing a weight-responsive element which engages or disengages the free-weight cables to a weight-support assembly. The device also provides self-spotting of dumbbells and allows motion of free-weight ends independent of each other.
Despite the improvements offered in the apparatus of application Ser. No. 09/201,434, use of rotary pawl clutches incorporating solenoids requires rotary electrical power transfer devices such as slip rings. These devices add equipment and maintenance cost to the apparatus. The weight of the chains and counterweights add significant inertia, which must be overcome with each extension and retraction of the free-weights.
Therefore an object of the present invention is to provide a self-spotting apparatus for free-weights which is simple, rugged and low in cost.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides weight-support assemblies capable of raising, lowering and statically supporting the full weight of the free-weights.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides immediate transfer of weight to the support assemblies upon release of the free-weights by the user.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which utilizes a weight-responsive element requiring the user to support substantially the full weight of the free-weights before disengagement from the support assemblies.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides two support assemblies for support of the barbells from both ends an well as separate and independent support for two dumbbells.
A further object of the present invention is to provide a self-spotting apparatus for free-weights in which disengagement of the support cables from the support assemblies allows independent motion of the support cables.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides for adjustment of support cable spacing to allow use of different types of free-weights.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides powered lifting of the free-weights without use of the user""s hands.
A further object of the present invention is to provide a self-spotting apparatus for free-weights comprising low-inertia components which provide engagement with the support assemblies.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which eliminates the need for rotary electrical connectors.
Yet another object of the present invention is to provide a self-spotting apparatus for free-weights which provides cable assemblies on each side, each cable assembly providing backup in case of cable breakage.
Still another object of the present invention is to provide a self-spotting apparatus for free-weights which provides backup of critical weigh transfer components.
A further object of the present invention is to provide a self-spotting apparatus for free-weights which provides xe2x80x9cfail-safexe2x80x9d electrical features to provide support of the free-weights upon loss of electrical power to the apparatus or to the electrical components.
The free-weight spotting apparatus of the present invention comprises two weight-support assemblies attached to a support stand. Each of two cable assemblies provides a connection between a free-weight and the respective support assembly through a weight-responsive engagement block constrained to reciprocating linear movement by a linear guide.
The weight-support assemblies provide static support to the free-weight when the weight-responsive engagement blocks are engaged to the respective support assemblies. The user must support the substantial weight of the free-weights in order to unlock and disengage the weight-responsive engagement blocks from the respective weight-support assemblies.
In the preferred embodiments, the weight-support assemblies are continuous chain loops supported vertically in the support stand. The weight-responsive engagement blocks comprise an engagement element such as a pawl which lock-engages the respective chain links in the weight-support direction. Also in the preferred embodiments, the pawls are biased continuously toward engagement by spring pressure and biased away from engagement by solenoids energized by pressure-sensitive switches disposed on the free-weight assembly. Lifting or support of the substantial weight of the free-weight by the user unlocks the pawls from the respective chain links and allows the bias force of the engaged solenoid to overcome the spring direction bias to disengage the pawl of the engagement block from the respective chain loops.
Once the blocks have been disengaged from the chain loops, the blocks reciprocate along the linear guides in response to raising and lowering of the free-weights by the user. When the blocks are both disengaged, free and independent vertical motion of both cables provides true xe2x80x9cfree-weightxe2x80x9d exercise.
Upon de-energizing the solenoids, as would occur by release of a pressure-sensitive switch on the free-weight by the user, the spring bias immediately engages the pawls of the blocks in links of the respective chain loops. Engagement is positive and independent of electrical power.
In the preferred embodiments, the chain loops are supported vertically by lower drive sprockets and upper idler sprockets. A brake motor drives the chain loops through a reducer, providing power raising and lowering of the free-weights when the engagement blocks are engaged to the chain loops. A direction switch located on the support stand energizes the respective forward or reverse windings of the motor through a controller located in the stand. A foot switch provides override to the raise direction of the brake motor. When de-energized, the brake motor provides the static support of the free-weight through the respective drive sprockets, chain loops, block and cable assembly.
Each cable assembly in the preferred embodiment is supported by at least one sheave in the upper portion of the stand between the free-weight and the engagement block. The engagement block acts as a counter-weight maintaining minimum tension on the cable assemblies and aiding disengagement of the pawls when the solenoids are energized. The counterweight force of the engagement blocks biases the blocks in a direction opposite of the lock-engage direction bias of the free-weights.
The preferred embodiments provide two cables arranged in parallel fashion for each cable assembly attaching the free-weights to the respective blocks. Both cables of each cable assembly are sized to carry the full design load of the apparatus. One of the cables of each cable assembly is slightly longer than the other cable in the pair so that in normal operation, only one cable carries the free-weight load. Should cable breakage occur on the tensioned cable, the second cable of the cable assembly will provide full support of the free-weight.
The preferred embodiments also provide pivoting support booms with sheaves at each end for supporting the respective cable assemblies. The outer ends of the support booms adjust to the desired spacing to allow barbell and dumbbell use.
Safety features of the preferred embodiments include dual chain loops including dual drive and idler sprockets for each support assembly, dual engagement pawls, engagement springs and solenoids on each engagement block, and dual, series-connected pressure-sensitive switches on the free-weight assembly such as a barbell. In this manner, neither failure of any one of the dual components, nor power failure to the apparatus will result in the loss of support for the free-weight.
An alternative embodiment utilizes a ratchet bar fixed vertically in the support stand for each of the weight-support assemblies. An engagement block riding on vertical guides comprises a pawl or latch plate which engages teeth of the ratchet bar. Cable assemblies connected each end of a free-weight to the engagement blocks and are supported by cable sheaves on the upper portion of the support stand. In still other embodiments, the linear guide and support assembly are integral components, guiding and engaging the engagement blocks.